Semiconductor package using flip-chip mounting technique

ABSTRACT

A semiconductor package using flip-chip mounting technique is disclosed. The semiconductor package includes: a semiconductor device provided with a plurality of first pads extending from the semiconductor device; a substrate provided with a plurality of second pads extending from the substrate at positions in registry with the location of the first pads of the semiconductor device; and an anisotropic conductive material interposed between the plurality of first pads and the plurality of second pads to electrically connect the first pads to associated second pads, the anisotropic conductive material positioned at discrete locations around the semiconductor device, thereby providing unobstructed clearance at desired locations between the semiconductor device and the substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, in general, to semiconductor packagesusing flip-chip mounting techniques and, more particularly, to asemiconductor package in which a semiconductor device is mounted usingboth a flip-chip mounting technique and an anisotropic conductivematerial.

2. Description of the Related Art

In recent years, micromachining techniques, for producing micro-opticalelements, micro-optical sensors, micro-bio-chips, andmicro-radio-communication devices, such as micro-mirrors, micro-lensesand micro-switches, using semiconductor device manufacturing processes,have been actively studied.

To use semiconductor devices, manufactured through the micromachiningtechniques, in practical applications, semiconductor packages must bemanufactured.

Semiconductor packaging techniques are complex techniques which includea variety of steps for producing the semiconductor devices and the finalproducts. In recent years, semiconductor packaging techniques have beenquickly and highly developed such that one million or more cells can beintegrated in a package. Particularly, non-memory semiconductor devicesare highly developed such that the devices have a great number of I/Opins, a large die size, a great heat dissipation capacity, highlyimproved electrical functions, etc. However, the conventionalsemiconductor packaging techniques for packaging the non-memorysemiconductor devices cannot keep pace with the rapid development ofsemiconductor devices.

The semiconductor packaging techniques are very important techniqueswhich determine the operational performance, sizes, costs andoperational reliability of final electronic products. Particularly, thesemiconductor packaging techniques play a key role in the manufacture ofrecently developed electronic products which aim for high electronicperformances, smallness/high density, low power consumption,multifunctionality, ultrahigh signal processing rates and permanentoperational reliability of the products.

To meet the above-mentioned recent trends, a flip-chip bondingtechnique, which is a kind of technique for electrically connecting asemiconductor chip to a substrate, has been actively studied, proposedand used. However, a conventional flip-chip bonding technique mustexecute complicated bonding processes using solder, which includeapplying solder flux onto a substrate, arranging a chip having solderbumps relative to the substrate having surface electrodes, executing thereflow of solder bumps, removing remaining flux, and applying andhardening underfill, thus increasing the costs of final products.

Therefore, in an effort to simplify the complicated processes of theconventional flip-chip bonding techniques, a wafer-phase semiconductorpackaging technique, in which a polymer material, functioning as bothflux and underfill, is applied to a semiconductor wafer, has beenactively studied and developed. Furthermore, a flip-chip bondingtechnique using a conductive adhesive, which is advantageous in that itcan reduce production costs, provide microelectrode pitches, and can beenvironment-friendly because it does not use flux or lead, and in whichprocesses are executed at low temperatures, has been actively studiedand developed.

Conventional conductive material layers are classified into two types:anisotropic conductive material layers and isotropic conductive materiallayers. A conductive material layer comprises conductive particles, suchas Ni, Au/polymer, or Ag particles, and a base resin, such as athermosetting resin, thermoplastic resin, or blend type insulating resinproduced by mixing the properties of the thermosetting resin and thethermoplastic resin.

FIG. 1A is a sectional view illustrating a conventional anisotropicconductive film. As shown in FIG. 1A, the conventional anisotropicconductive film 10 is a polymer resin-based film, with conductiveparticles 20 finely dispersed in the conductive film 10 to impartconductivity to the film. A releasing film 30 is attached to eachsurface of the anisotropic conductive film 10.

FIG. 1B is a sectional view illustrating a conventional flip-chipbonding technique for producing a semiconductor package using theanisotropic conductive film of FIG. 1A. As shown in the drawing, a firstrelease film 30 is removed from one surface of the anisotropicconductive film 10 and the exposed surface of the anisotropic conductivefilm 10 is thermally compressed and adhered to a substrate 50.Thereafter, a second release film 30 is removed from the other surfaceof the anisotropic conductive film 10. An IC chip 40 having bumps 45 isplaced on the exposed surface of the conductive film 10 such that thebumps 45 of the IC chip 40 are aligned with electrodes 55 of thesubstrate 50. Thereafter, the anisotropic conductive film 10, having theIC chip 40 and the substrate 50, is subjected to thermal compression, sothat the conductive particles in the anisotropic conductive film areplastically deformed, thus mechanically and electrically coupling thebumps 45 to the electrodes 55.

However, to use the flip-chip bonding technique, which can producesemiconductor packages using anisotropic conductive films, in theprocess of producing a semiconductor device using a micromachiningtechnique, it is required to solve some technical problems in advance.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind theabove-mentioned requirements occurring in the related art, and an objectof the present invention is to provide a semiconductor package which ismanufactured using a flip-chip mounting technique capable of providing areliable electrical connection between a semiconductor substrate and atransparent substrate.

Another object of the present invention is to provide a semiconductorpackage which is manufactured using a flip-chip mounting techniquecapable of providing a desired joining strength between thesemiconductor substrate and the transparent substrate even when a lowtemperature and a low compression load are used in the process ofjoining the semiconductor substrate to the transparent substrate.

In order to achieve the above objects, there is provided a semiconductorpackage using flip-chip mounting technique, comprising: a semiconductordevice provided with a plurality of first pads extending from thesemiconductor device; a substrate provided with a plurality of secondpads extending from the substrate at positions in registry with thelocation of the first pads of the semiconductor device; and ananisotropic conductive material interposed between the plurality offirst pads and the plurality of second pads to electrically connect thefirst pads to associated second pads, the anisotropic conductivematerial positioned at discrete locations around the semiconductordevice, thereby providing unobstructed clearance at desired locationsbetween the semiconductor device and the substrate.

The semiconductor package using flip-chip mounting technique accordingto the present invention preferably further comprises a plurality ofbumps provided on the first pads of the semiconductor device, each ofthe bumps extending in the direction of a corresponding second pad.

In the semiconductor package using flip-chip mounting techniqueaccording to the present invention, the substrate is preferablytransparent to light. The transparent substrate is preferably providedwith an anti-reflective coating on at least one of the surfaces thereof,thus increasing light transmissivity of incident light.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description when taken in conjunction with the accompanyingdrawings, in which:

FIG. 1A is a sectional view illustrating a conventional anisotropicconductive film;

FIG. 1B is a sectional view illustrating a conventional flip-chipbonding technique for producing a semiconductor package using theanisotropic conductive film of FIG. 1 a;

FIG. 2 is a sectional view of a semiconductor package manufactured usinga flip-chip mounting technique according to an embodiment of the presentinvention; and

FIG. 3 is a sectional view of a light modulator module packagemanufactured according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Herein below, a semiconductor package manufactured using a flip-chipmounting technique according to the present invention will be describedin detail with reference to the accompanying drawings.

FIG. 2 is a sectional view of a semiconductor package manufactured usinga flip-chip mounting technique according to an embodiment of the presentinvention.

As shown in FIG. 2, the semiconductor package 100 manufactured using theflip-chip mounting technique according to the present inventioncomprises a semiconductor substrate 110 provided with a plurality ofupper pads 120 on a lower surface thereof, a transparent substrate 130provided with a plurality of lower pads 140 on an upper surface thereof,and an anisotropic conductive material layer 160 interposed between eachof the upper pads 120 and an associated lower pad 140. The semiconductorpackage 100 manufactured using the flip-chip mounting techniqueaccording to the present invention preferably further comprises a bump150 that is provided on each of the upper pads 120. The bump 150 extendsin the direction of a corresponding lower pad 140. Furthermore, thesemiconductor package 100 of the present invention may further comprisea bump (not shown) that is provided on each of the lower pads 140 of thetransparent substrate 130. This bump extends in the direction of acorresponding upper pad 120.

The semiconductor substrate 110 is integrated with micro-machines, suchas micro-optical elements, micro-optical sensors, micro-bio-chips, andmicro-radio-communication devices. For example, light modulators may beintegrated in the lower surface of the semiconductor substrate 110.

Furthermore, because the semiconductor substrate 110 is provided withthe plurality of upper pads 120 on the lower surface thereof, thesemiconductor substrate 110 can receive control signals or electricsignals through the upper pads 120.

The transparent substrate 130 is formed of an optically transparentmaterial so that incident light can be transmitted through thetransparent substrate 130. To enhance the light transmissivity of thetransparent substrate 130, it is preferable to form an anti-reflectivecoating on at least one of opposite surfaces of the transparentsubstrate 130.

Furthermore, because the transparent substrate 130 is provide with theplurality of lower pads 140 on the upper surface thereof, thetransparent substrate 130 can transmit control signals or electricsignals to the semiconductor substrate 110 through the lower pads 140,thus controlling the micro-machines integrated in the semiconductorsubstrate 110.

The bumps 150 are respectively formed on the upper pads 120 of thesemiconductor substrate 110 and transmit the electric signals betweenthe semiconductor substrate 110 and the transparent substrate 130.

In accordance with another embodiment of the present invention,micro-electro-mechanical systems (MEMS) may be integrated in the lowersurface of the semiconductor substrate 110. In the above case, thesemiconductor package preferably requires a space defined therein toallow the MEMS to be actuated in the space. The bumps 150 preferably actas spacers to create the space in the semiconductor package.

The anisotropic conductive material layers 160 are configured such thatconductive particles 161, such as metal-coated plastic particles ormetal particles, are dispersed in an adhesive, such as epoxy.

In the embodiment of the present invention, the anisotropic conductivematerial layers 160 are processed as follows to electrically connect theupper pads 120 to the lower pads 140. The anisotropic conductivematerial layers 160 are primarily placed between the upper pads 120 ofthe semiconductor substrate 110 and the lower pads 140 of thetransparent substrate 130, and then heated at a low temperature andcompressed with a low compression load. Thus, the conductive particles161 dispersed in the anisotropic conductive material layers 160 arebrought into close contact with the upper and lower pads 120 and 140,thereby electrically connecting the upper pads 120 to the associatedlower pads 140. In the above case, parts of the anisotropic conductivematerial layers 160 located on uncompressed parts of the upper and lowerpads 120 and 140 are not electrically connected to each other becausethe conductive particles 161 in the designated parts are spaced apartfrom each other.

Therefore, in the semiconductor package 100 manufactured using aflip-chip mounting technique according to the present invention, theupper pads 120 of the semiconductor substrate 110 can be electricallyconnected to the lower pads 140 of the transparent substrate 130 using alow compression load at a low temperature. Thus, the upper pads 120 areelectrically connected to the lower pads 140 through a thermalcompression process using a low compression load that does not causecracks in the transparent substrate 130.

In a preferred embodiment of the present invention, an anisotropicconductive film, processed such that part of the film to be brought intoclose contact with the upper pads 120 and the lower pads 140, 241, 242and 243 remains, may be used as the anisotropic conductive materiallayer 160.

In another preferred embodiment of the present invention, an anisotropicconductive solution, prepared by mixing conductive particles 161, suchas metal-coated plastic particles or metal particles, with an adhesive162, such as epoxy, may be used as the anisotropic conductive materiallayer 160. In the above case, the anisotropic conductive material layer160 may be formed by shallowly dipping the upper pads 120 of thesemiconductor substrate 110 (or the bumps 150 in the case of upper pads120 having the bumps 150) in the anisotropic conductive solution.Alternatively, the anisotropic conductive material layer 160 may beformed by lightly stamping the upper pads 120 of the semiconductorsubstrate 110 (or the bumps 150 in the case of upper pads 120 having thebumps 150) onto a fabric laden with the anisotropic conductive solution.

FIG. 3 is a sectional view illustrating a light modulator module packagemanufactured according to the present invention.

As shown in FIG. 3, the light modulator module package 200 manufacturedaccording to the present invention includes a transparent substrate 230,a light modulator device 211, and a plurality of drive integratedcircuits 212 and 213.

The transparent substrate 230 is formed of an optically transparentmaterial so that incident light can be transmitted through the substrate230. The light modulator device 211, the plurality of drive integratedcircuits 212 and 213, and a plurality of lower pads 241, 242 and 243 totransceive electrical signals are formed on the surface of thetransparent substrate 230.

The light modulator device 211 is a semiconductor device integrated witha refractive, reflective or transmissive light modulator 211 a on thelower surface thereof. The light modulator device 211 modulates theincident light passing through the transparent substrate 230, and thenemits the modulated light to the outside. The light modulator device 211is provided with a plurality of upper pads 221 on the lower surfacethereof. The upper pads 221 of the light modulator device 211 areelectrically connected to the associated lower pads 241 of thetransparent substrate 230 by means of anisotropic conductive materiallayers 261.

The plurality of drive integrated circuits 212 and 213 are placed aroundthe light modulator device 211 and provide drive voltage to drive thelight modulator device 211. In a manner similar to the light modulatordevice 211, the drive integrated circuits 212 and 213 are each providedwith a plurality of upper pads 222 or 223 on the lower surface thereof.The upper pads 222 and 223 of the drive integrated circuits 212 and 213are electrically connected to the associated lower pads 242 and 243 ofthe transparent substrate 230 through anisotropic conductive materiallayers 262 and 263.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

As described above, the present invention provides a semiconductorpackage manufactured using a flip-chip mounting technique. In thesemiconductor package according to the present invention, a reliableelectrical connection between a plurality of upper pads of asemiconductor substrate and a plurality of lower pads of a transparentsubstrate can be accomplished through a thermal compression processusing a low compression load at a low temperature.

To produce the semiconductor package using the flip-chip mountingtechnique according to the present invention, a thermal compressionprocess using a low compression load is executed so that the transparentsubstrate does not crack.

Furthermore, in the semiconductor package using the flip-chip mountingtechnique according to the present invention, the electrical connectionof the upper pads of the semiconductor substrate to the lower pads ofthe transparent substrate is easily accomplished, so that the process ofmanufacturing the semiconductor package is simplified, and accomplishesthe recent trend of hyperfineness, high-functionality, smallness andcompactness of semiconductor packages.

1. A semiconductor package using flip-chip mounting technique,comprising: a semiconductor device provided with a plurality of firstpads extending from the semiconductor device; a substrate provided witha plurality of second pads extending from the substrate at positions inregistry with the location of the first pads of the semiconductordevice; and an anisotropic conductive material interposed between theplurality of first pads and the plurality of second pads to electricallyconnect the first pads to associated second pads, the anisotropicconductive material positioned at discrete locations around thesemiconductor device, thereby providing unobstructed clearance atdesired locations between the semiconductor device and the substrate;and wherein the semiconductor device comprises an optical modulatingdevice and the substrate is transparent to light, so that light istransmitted through the transparent substrate and is incident on theoptical modulating device, and is reflected from the optical modulatingdevice to be output through the transparent substrate.
 2. Thesemiconductor package according to claim 1, wherein the light travels toand from the optical modulating device through the unobstructedclearance provided between the optical modulating device and thetransparent substrate due to positioning of the anisotropic conductivematerial at discrete locations around the semiconductor device.
 3. Thesemiconductor package according to claim 1, wherein an anti-reflectivecoating is disposed on at least one of the surfaces of the transparentsubstrate to increase light transmissivity of incident light.